Abstract #0807

Dynamic Manganese-Enhanced MRI Reveals Dominant Modulation of Myocardial L-Type Calcium Channel Flux by Neuronal, Not Endothelial Nitric Oxide Synthase in Mice

Moriel H. Vandsburger¹, Brent A. French^1,2, Christopher M. Kramer^2,3, Frederick H. Epstein^1,2

¹Biomedical Engineering, University of Virginia, Charlottesville, VA, USA; ²Radiology, University of Virginia, Charlottesville, VA, USA; ³Medicine, University of Virginia, Charlottesville, VA, USA

Modulation of L-Type Calcium Channel (LTCC) flux plays an important role in calcium cycling and cardiomyocyte contractility. Manganese (Mn2+) enters cardiomyocytes through the LTCC and shorterns T1 proportionatly. Modulation of LTCC flux by neuronal (nNOS) and endothelial (eNOS) isoforms of nitric oxide synthase is unclear. The uptake of Mn2+ was examined in wild type (WT), nNOS-/-, and eNOS-/- mice at baseline and with dobutamine using an ECG-gated saturation recovery pulse sequence with constant repetition time (TR) of 200ms. Whereas baseline LTCC flux was higher in nNOS-/- mice and unchanged with dobutamine, LTCCI increased with dobutamine in WT and eNOS-/- mice.